Blowing device and vacuum cleaner provided with same

ABSTRACT

A blowing device includes a motor including a rotor rotatable about a central axis extending in an up-down direction, an impeller fixed to the rotor and rotatable together with the rotor, a motor housing on a radial direction outer side with respect to the motor and housing at least a portion of the motor, a blower case on the radial direction outer side with respect to the motor housing, and connection portions that connect the motor housing and the blower case to each other in the radial direction. The connection portions include a first connection portion with a communication hole that communicates an inner portion of the motor housing and an outer portion of the blower case to each other.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2017-244949 filed on Dec. 21, 2017. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to a blowing device and a vacuum cleaner provided with the same.

2. Description of the Related Art

Hitherto, a blowing device that includes a plurality of connection portions is known. The blowing device is mounted in a vacuum cleaner or the like. In a known electric blower, air that has been suctioned through an intake port with a rotation of an impeller passes through the impeller, a diffuser, and an inside of a bracket while cooling a stator, a rotor, and the like and is ultimately discharged to a portion external to the electric blower.

However, in the known electric blower, air directly enters into the bracket from the diffuser to cool the stator, the rotor, and the like. Accordingly, air blowing efficiency of the electric blower decreases.

SUMMARY OF THE INVENTION

A blowing device according to an exemplary embodiment of the present disclosure includes a motor including a rotor rotatable about a central axis extending in an up-down direction, an impeller that is fixed to the rotor and that is rotatable together with the rotor, a housing that is disposed on a radial direction outer side with respect to the motor and that houses at least a portion of the motor, a blower case disposed on the radial direction outer side with respect to the housing, and a plurality of connection portions that connect the housing and the blower case to each other in the radial direction. The plurality of connection portions include a first connection portion including a communication hole that communicates an inner portion of the housing and an outer portion of the blower case to each other.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a blowing device.

FIG. 2 is an external view of the blowing device illustrating a blower case in a transparent manner.

FIG. 3 is a longitudinal section illustrating a configuration example of the blowing device.

FIG. 4 is a cross-sectional view of the blowing device viewed in an axial direction.

FIG. 5A is an enlarged view illustrating a configuration example of a communication hole.

FIG. 5B is a cross-sectional view of a vicinity of the communication hole viewed in a circumferential direction.

FIG. 5C is a cross-sectional view of a vicinity of the communication hole viewed from an axial direction upper side.

FIG. 5D is a cross-sectional view of another configuration of a vicinity of a communication hole viewed in the circumferential direction.

FIG. 6 is an example of a vacuum cleaner in which the blowing device is mounted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. Note that in the present specification, a rotation axis of a motor 110 of a blowing device 100 is referred to as a “central axis CA”, and a direction parallel to the central axis CA is referred to as an “axial direction”. A direction oriented in the axial direction from a substrate 6 described later towards an impeller 120 described later is referred to as an “axial direction upper side” that is a first side in the axial direction, and a direction oriented in the axial direction from the impeller 120 towards the substrate 6 is referred to as an “axial direction lower side” that is a second side in the axial direction. In each of the components, an end portion on the axial direction upper side is referred to as an “upper end portion”, and an end position on the axial direction upper side is referred to as an “upper end”. In each of the components, an end portion on the axial direction lower side is referred to as a “lower end portion”, and an end position on the axial direction lower side is referred to as a “lower end”. Furthermore, among the surfaces of the components, a surface oriented towards the axial direction upper side is referred to as an “upper surface”, and a surface oriented towards the axial direction lower side is referred to as an “undersurface”.

A direction orthogonal to the central axis CA is referred to as a “radial direction”. A direction in the radial direction oriented towards the central axis CA is referred to as a “radial direction inner side” and a direction in the radial direction distancing away from the central axis CA is referred to as a “radial direction outer side”. In each of the components, an end portion on the radial direction inner side is referred to as a “radial direction inner end portion”, and an end position on the radial direction inner side is referred to as a “radial direction inner end”. In each of the components, an end portion on the radial direction outer side is referred to as a “radial direction outer end portion”, and an end position on the radial direction outer side is referred to as a “radial direction outer end”. Furthermore, in the lateral surface of each component, a lateral surface oriented towards the radial direction inner side is referred to as a “radial direction inner lateral surface”, and a lateral surface oriented towards the radial direction outer side is referred to as a “radial direction outer lateral surface”.

A rotation direction of a rotor 1 about the central axis CA may be referred to as a “circumferential direction”. Furthermore, a direction in which the rotor 1 moves forward in the circumferential direction is referred to as a “forward rotation direction FRD”, and a direction in which the rotor 1 moves backwards in the circumferential direction is referred to as a “backward rotation direction BRD”. In other words, the “backward rotation direction BRD” is a direction opposite to the “forward rotation direction FRD”. In each of the components, an end portion in the forward rotation direction FRD is referred to as a “forward rotation direction end portion” and an end position in the forward rotation direction FRD is referred to as a “rotation direction front end”. Furthermore, in each of the components, an end portion in the backward rotation direction BRD is referred to as a “backward rotation direction end portion”, and an end position in the backward rotation direction BRD is referred to as a “rotation direction back end”.

Note that the names of the directions, the end portions, and the surfaces described above do not illustrate the actual positional relationships and directions when installed in a piece of equipment.

The blowing device 100 according to an exemplary embodiment of the present disclosure will be described first. FIG. 1 is an external view of the blowing device 100. FIG. 2 is an external view of the blowing device 100 illustrating the blower case 32 in a transparent manner. FIG. 3 is a longitudinal section illustrating a configuration example of the blowing device 100. FIG. 4 is a cross-sectional view of the blowing device 100 viewed in the axial direction. Note that FIG. 3 illustrates a cross section structure in which the blowing device 100 is imaginarily cut along a plane including the central axis CA. Furthermore, FIG. 4 is a cross section structure in which the blowing device 100 is imaginarily cut along a plane that is parallel to the radial direction including the dot and dash line A-A in FIG. 3.

The blowing device 100 includes the motor 110, the impeller 120, and a casing 3. The impeller 120 is a vanes wheel including a plurality of vanes 121 capable of rotating about the central axis CA. The impeller 120 is provided at an upper portion of the motor 110. The impeller 120 is capable of rotating about the central axis that extends in an up-down direction. The casing 3 houses at least a portion of the motor 110 and at least a portion of the impeller 120.

The motor 110 is of an inner rotor type and drives and rotates the impeller 120. The motor 110 includes the rotor 1, a stator 2, a bracket 4, and the substrate 6.

The rotor 1 is rotatable about the central axis CA extending in the up-down direction. In other words, the motor 110 includes the rotor 1 rotatable about the central axis CA that extends in the up-down direction. The rotor 1 includes a shaft 10, a magnet 11, and a holding member 12. The shaft 10 is a rotating shaft that extends upwards and downwards in the axial direction. The impeller 120 is attached to the upper portion of the shaft 10. In other words, the impeller 120 is fixed to the rotor 1 and is rotatable together with the rotor 1. Furthermore, the vanes 121 are rotatable in the rotation direction of the rotor 1. The magnet 11 has a tubular shape extending in the axial direction and is fixed to an outer lateral surface of the shaft 10 in the radial direction. The holding member 12 is fixed to an outer lateral surface of the magnet 11 in the radial direction. The holding member 12 is disposed on the radial direction inner side with respect to the stator 2 and opposes the stator 2 in the radial direction.

The motor 110 further includes the stator 2 disposed on a radial direction outer side of the rotor 1. The stator 2 is rotated by driving the rotor 1. The stator 2 includes a stator core 21, an insulator 22, and a plurality of coil portions 23. The stator core 21 is formed of laminated steel plates that are electromagnetic steel plates laminated in the axial direction, for example, and is fixed to the casing 3. The coil portions 23 are provided in the stator core 21 with the insulator 22 in between. In other words, the stator 2 includes the stator core 21 provided with the coil portions 23. The stator core 21 includes a core back 21C and teeth 21T. As illustrated in FIG. 4, the core back 21C has an annular shape surrounding the central axis CA. Not that an “annular shape” herein includes, in addition to a case in which the entire circumstance is continuously connected, a case in which a portion of the circumstance is discontinuous. Furthermore, “the core back 21C having an annular shape” includes a case in which there are a plurality of core backs 21C and in which the plurality of core backs 21C are arranged in the circumferential direction. The teeth 21T each extend in the radial direction from the core back 21C towards the holding member 12. The insulator 22 is, for example, an insulating member formed using a resin material and covers at least a portion of the stator core 21, in particular, covers the teeth 21T. The coil portions 23 are winding members formed of conducting wires wound around the teeth 21T of the stator core 21 with the insulator 22 in between. In other words, the stator core 21 and the coil portions 23 are electrically insulated from each other with the insulator 22. Furthermore, the plurality of coil portions 23 are arranged in the circumferential direction around the shaft 10.

Furthermore, partial regions 21 a in a radial direction outer lateral surface of the stator core 21 are in contact with and are fixed to an inner surface of the casing 3. Hereinafter, the partial regions 21 a are referred to as “stator first regions 21 a”. Furthermore, other partial regions 21 b in the radial direction outer lateral surface of the stator core 21 that oppose the inner surface of the casing 3 in the radial direction with gaps 110 a in between are referred to as “stator second regions 21 b”. In other words, the radial direction outer lateral surface of the stator core 21 includes the stator first regions 21 a and the stator second regions 21 b. In the present embodiment, in the stator first regions 21 a, portions of a radial direction outer end portion of the core back 21C are in contact with and are fixed to a radial direction inner lateral surface of a cylindrical portion 312 of a motor housing 31, described later, of the casing 3.

The bracket 4 includes a lower bearing holder 41 and a lid portion 42. The lower bearing holder 41 rotatably supports the shaft 10 with a lower bearing 41 a interposed therebetween. Furthermore, the lower bearing holder 41 has a tubular shape extending in the axial direction. The lower bearing 41 a is provided on a radial direction inner lateral surface of the lower bearing holder 41. The shaft 10 passes through both the lower bearing 41 a and the lower bearing holder 41. Although not limited to any bearing in particular, a ball bearing, a sleeve bearing, or the like can be used as the lower bearing 41 a. The lid portion 42 extends towards the radial direction outer side from a lower end portion of the lower bearing holder 41 and covers an opening at a lower end portion of the casing 3.

In the present embodiment, the substrate 6 is disposed below the bracket 4 in the axial direction and is fixed to the lid portion 42 of the bracket 4. The substrate 6 is a plate-shaped circuit substrate and is formed of a resin material such as an epoxy resin. The substrate 6 is electrically connected to the coil portions 23 of the stator 2. The substrate 6 is electrically connected to a device and the like external to the motor 110 through a connection line (not shown) that is drawn out to the outside of the motor 110. Furthermore, an electronic component 61 is mounted on the substrate 6. Furthermore, the electronic component 61 includes a power supply circuit and a control circuit of the motor 110.

The casing 3 includes the motor housing 31, the blower case 32, and a plurality of connection portions 33. In other words, the blowing device 100 includes the motor housing 31, the blower case 32, and the plurality of connection portions 33. The motor housing 31, the blower case 32, and the connection portions 33 constitute the same member in the present embodiment, in other words, the motor housing 31, the blower case 32, and the connection portions 33 are an integral structure. However, not limited to the above example, at least one of the above may be a separate member, in other words, the above do not have to be an integral structure. Furthermore, communication holes 3 a are provided in the casing 3. The configuration of the communication holes 3 a will be described later.

The motor housing 31 houses at least a portion of the motor 110. In the present embodiment, the motor housing 31 houses the rotor 1 and the stator 2. The motor housing 31 has a tubular shape with a lid. The motor housing 31 includes an upper bearing holder 311 and the cylindrical portion 312.

The upper bearing holder 311 rotatably supports the shaft 10 with an upper bearing 311 a interposed therebetween. Furthermore, the upper bearing holder 311 extends in the radial direction. The upper bearing holder 311 is, at the center provided, with a through hole 311 b that penetrates thereof in the axial direction. The upper bearing 311 a is provided on a radial direction inner lateral surface of the through hole 311 b. The shaft 10 is inserted in the upper bearing 311 a together with the through hole 311 b. Although not limited to any bearing in particular, a ball bearing, a sleeve bearing, or the like can be used as the upper bearing 311 a.

The cylindrical portion 312 extends downwards in the axial direction from a radial direction outer end portion of the upper bearing holder 311. The cylindrical portion 312 is disposed on the radial direction outer side with respect to the motor 110. In other words, the motor housing 31 is disposed on the radial direction outer side with respect to the motor 110. The radial direction inner lateral surface of the cylindrical portion 312 is, in the radial direction outer lateral surface of the stator core 21, in contact with the stator first regions 21 a and is separated from the stator second regions 21 b in the radial direction. In other words, the stator first regions 21 a are in contact with the inner surface of the motor housing 31. Furthermore, the stator second regions 21 b having the gaps 110 a in the radial direction oppose the inner surface of the motor housing 31.

The blower case 32 houses the impeller 120. The blower case 32 is disposed on a radial direction outer side of the motor housing 31. An intake port 32 a is provided at an upper end portion of the blower case 32. The blower case 32 forms a gap with the motor housing 31. The gap is a distribution passage of the airflow generated by the rotation of the impeller 120. A ventilation port 32 b is provided at a lower end portion of the blower case 32 and between a radial direction outer lateral surface of the motor housing 31. The air drawn in through the intake port 32 a with the rotation of the impeller 120 flows downwards in the axial direction through a portion between the motor housing 31 and the blower case 32 and is sent out to a portion outside the casing 3 through the ventilation port 32 b.

The connection portions 33 connect the motor housing 31 and the blower case 32 to each other in the radial direction. Inner end portions of the connection portions 33 are connected to the radial direction outer lateral surface of the motor housing 31. Radial direction outer end portions of the connection portions 33 are connected to a radial direction inner lateral surface of the blower case 32.

Furthermore, the connection portions 33 are stator blades disposed between the motor housing 31 and the blower case and are arranged in a plural number in the circumferential direction. Each of the connection portions 33 extends in the axial direction. As upper end portions of the connection portions 33 extend towards the axial direction upper side, the upper end portions curve towards the backward rotation direction BRD. Accordingly, the airflow generated by the rotation of the impeller 120 easily flows between adjacent connection portions 33 in the circumferential direction.

A configuration of the communication holes 3 a will be described next. FIG. 5A is an enlarged view illustrating a configuration example of the communication hole 3 a. FIG. 5B is a cross-sectional view of a vicinity of the communication hole 3 a viewed in the circumferential direction. FIG. 5C is a cross-sectional view of a vicinity of the communication hole 3 a viewed from the axial direction upper side. FIG. 5D is a cross-sectional view of another configuration of a vicinity of the communication hole 3 a viewed in the circumferential direction. Note that FIG. 5A corresponds to a portion surrounded by a dot and dash line in FIG. 1. Furthermore, in order to facilitate understanding of the configuration, the blower case 32 is depicted in a transparent manner in FIG. 5A. FIGS. 5B and 5D illustrate cross section structures taken along a dot and dash line B-B in FIG. 5A. FIG. 5C illustrates a cross section structure taken along a dot and dash line C-C in FIG. 5A.

As described above, the communication holes 3 a are provided in the casing 3. When viewed in the radial direction, each communication hole 3 a is, among the plurality of connection portions 33, formed inside a corresponding single connection portion 7. More specifically, when viewed in the radial direction, the communication hole 3 a is formed between a forward rotation direction end portion and a backward rotation direction end portion of the connection portion 7, and between an upper end and a lower end of the connection portion 7. Furthermore, when viewed in the circumferential direction, a radial direction inner end portion of the communication hole 3 a penetrates the cylindrical portion 312 of the motor housing 31 in the radial direction, a radial direction middle portion of the communication hole 3 a penetrates a first connection portion 7 in the radial direction, and a radial direction outer end portion of the communication hole 3 a penetrates the blower case 32 in the radial direction. As described above, the plurality of connection portions 33 include the first connection portions 7 constituting the communication holes 3 a. Hereinafter, the connection portion 7 is referred to as a “first connection portion 7”. Note that among the plurality of connection portions 33, connection portions 331 other than the first connection portions 7 are referred to as “second connection portions 331”.

In the upper portion of the first connection portion 7, a forward rotation direction lateral surface 7 a of the first connection portion 7 is a curved surface that extends downwards in the axial direction as the lateral surface 7 a extends in the forward rotation direction FRD. In the upper portion of the first connection portion 7, a backward rotation direction lateral surface 7 b of the first connection portion 7 is a curved surface that extends downwards in the axial direction as the lateral surface 7 a extends in the forward rotation direction FRD. Furthermore, the forward rotation direction lateral surface 7 a protrude in the forward rotation direction FRD and towards the axial direction upper side. Furthermore, the backward rotation direction lateral surface 7 b is recessed in the forward rotation direction FRD and towards the axial direction upper side. With the curve of the forward rotation direction lateral surface 7 a described above, the airflow can be distributed in a smooth manner between the first connection portion 7 and the connection portion adjacent to the first connection portion 7 in the forward rotation direction FRD. Furthermore, with the curve of the backward rotation direction lateral surface 7 b described above, the airflow can be distributed in a smooth manner between the first connection portion 7 and the connection portion 33 adjacent to the first connection portion 7 in the backward rotation direction BRD. Accordingly, the air blowing efficiency of the blowing device 100 can be improved.

As described above, each communication hole 3 a penetrates the cylindrical portion 312 of the motor housing 31, the corresponding first connection portion 7, and the blower case 32 in the radial direction. In other words, each communication hole 3 a communicates the inside of the motor housing 31 and the outside of the blower case 32 to each other. As illustrated in FIG. 4, the communication holes 3 a are connected to the gaps 110 a between the stator second regions 21 b in the radial direction outer lateral surface of the stator core 21 and the inner surface of the cylindrical portion 312 of the motor housing 31. The gaps 110 a are in communication with the outside of the blowing device 100 through a lower end portion of the motor housing 31. By providing the communication holes 3 a in the casing 3, the inside of the motor housing 31 and the outside of the blower case 32 are in communication with each other through the communication holes 3 a. Accordingly, air can be distributed between the inside of the motor housing 31 and the outside of the blower case 32 through the communication holes 3 a. For example, a portion of the airflow that flows between the first connection portion 7 and the connection portion 33 adjacent to the first connection portion 7 and that is discharged towards the axial direction lower side flows into the motor housing 31 through the lower end portion of the motor housing 31 and is discharged to the outside of the blower case 32 through the communication holes 3 a. Furthermore, such a circulation of the airflow does not have an adverse effect on the airflow that is generated by the rotation of the impeller 120 and that flows into the portion between the first connection portion 7 and the connection portion 33 adjacent to the first connection portion 7 in the circumferential direction. Accordingly, the motor 110 can be cooled by the above airflow without decreasing the air blowing efficiency.

Furthermore, an opening region at the radial direction inner end of each communication hole 3 a overlaps a portion of the motor 110 in the radial direction. More specifically, the opening region at the radial direction inner end of each communication hole 3 a overlaps a portion of the stator 2 in the radial direction. Note that the opening region at the radial direction inner end of each communication hole 3 a is the radial direction inner end portion of the communication hole 3 a that is open in the inner surface of the cylindrical portion 312 of the motor housing 31. In other words, in the inner surface of the cylindrical portion 312 of the motor housing 31, each communication hole 3 a is open towards a portion of the motor 110 and, when viewed in the radial direction, overlaps a portion of the motor 110. More specifically, each communication hole 3 a opens towards a portion of the stator 2 and overlaps a portion of the stator 2. With such a configuration, each communication hole 3 a open in the inner surface of the motor housing 31 directly faces a portion of the motor 110 such as, for example, the stator 2 or, more specifically, directly faces a portion of the stator 2 such as, for example, the stator core 21. Accordingly, the motor 110 can be cooled by the airflow discharged from between a portion of the motor 110 and the motor housing 31 to the outside of the blower case 32 through the communication holes 3 a, for example.

In the present embodiment, the communication holes 3 a overlap portions of the stator second regions 21 b of the stator 2 in the radial direction and, in particular, overlap portions of radial direction outer lateral surfaces of the core back 21C in the stator second regions 21 b in the radial direction. In other words, the opening region in the radial direction inner end of each communication hole 3 a overlaps a portion of the corresponding stator second region 21 b in the radial direction. With the above configuration, the flow of the airflow flowing into the inside of the motor housing 31 from the axial direction lower side of the motor housing 31 is facilitated by having the communication holes 3 a be in communication with the gap between the motor housing 31 and the stator 2; accordingly, the cooling efficiency of the stator 2 is improved.

Note that in the present embodiment, as illustrated in FIG. 5B, for example, the stator 2 is not in contact with the motor housing 31 at positions that are the same as those of the stator second regions 21 b in the circumferential direction. However, not limited to the example described above, as illustrated in FIG. 5D, at a position that is the same as that of the stator second region 21 b in the circumferential direction, a portion of the stator 2 may be in contact with the motor housing 31 at a portion on the axial direction lower side with respect to the communication hole 3 a. For example, in FIG. 5D, a portion of the insulator 22 on the axial direction lower side with respect to the communication hole 3 a covers an axial direction lower portion of the stator core 21 and is in contact with the motor housing 31. Accordingly, the gap 110 a is closed on the axial direction lower side with respect to the communication hole 3 a. With the above configuration, among the surfaces of the stator 2, a portion of a surface region 22 a of the insulator 22 disposed on the axial direction lower side with respect to the stator second region 21 b is in contact with the motor housing 31. Hereinafter, each of the above surface region 22 a is referred to as a “stator third region 22 a”. Note that in FIG. 5D, in the stator third region 22 a, only the above-described portion of the radial direction outer lateral surface of the insulator 22 is in contact with the motor housing 31. However, not limited to the example described above, the entire stator third region 22 a may be in contact with the motor housing 31. Such a configuration can be provided by having the stator second region 21 b have a tapered shape that is tapered towards the radial direction outer side as the stator second region 21 b extends towards the axial direction lower side. As described above, the surface of the stator 2 includes the stator third region 22 a in which a portion thereof is in contact with the motor housing 31 on at least the axial direction lower side with respect to the communication hole 3 a. The stator third region 22 a is disposed on the axial direction lower side of the stator second region 21 b. In other words, the stator 2 further includes the stator third region 22 a disposed on the axial direction lower side of the stator second region 21 b. At least a portion of each stator third region 22 a is in contact with the motor housing 31. According to the above configuration, each gap 110 a is closed at the axial direction lower side with respect to the corresponding communication hole 3 a by a portion of the stator 2 that includes the stator third region 22 a on the surface thereof. Accordingly, the airflow inside the casing 3 that flows into the gaps 110 a from the axial direction upper side of the stator core 21 can be sent out to the outside of the casing 3 through the communication holes 3 a. In other words, compared with a case in which the gaps 110 a are not closed by the stator third regions 22 a, the air inside the casing 3 can be prevented from being guided to the communication holes 3 a without passing through the gaps 110 a and cooling the axial direction upper side region of the stator core 21. Accordingly, the stator core 21 can be cooled more efficiently.

Furthermore, the upper end of the opening region in the radial direction inner end of each communication hole 3 a is, as illustrated in FIG. 5B, disposed on the axial direction upper side with respect to the upper end of the stator core 21. With the above configuration, since the upper end of each communication hole 3 a is situated above the stator core 21 in the axial direction, the air above the stator core 21 in the axial direction can be guided to the communication hole in an efficient manner.

As the bores of the communication holes 3 a become larger, the airflow flows more easily from the inside to the outside of the casing 3 through the communication holes 3 a. Accordingly, desirably as illustrated in FIG. 5A, a width W1 of the first connection portion 7 in the circumferential direction is larger than a width W2 of the second connection portions 331, which are connection portions other than the first connection portion 7 among the plurality of connection portions 33, in the circumferential direction. With the above configuration, the widths of the communication holes 3 a in the circumferential direction can be enlarged. Accordingly, an improvement in the cooling effect of the motor 110 can be achieved.

Furthermore, desirably, a largest width Wam of each communication hole 3 a in the axial direction is larger than a largest width Wrm of the communication hole 3 a in the circumferential direction (see FIG. 1). In other words, desirably, in each communication hole 3 a, the axial direction is the longitudinal direction and the circumferential direction is the short direction. With the above configuration, for example, the airflow that flows into the motor housing 31 from the axial direction lower side of the motor housing 31 and that is discharged through the communication holes 3 a is in contact with the motor 110 longer. Accordingly, the motor 110 can be cooled more effectively.

While the arrangement of the communication holes 3 a is not limited to any arrangement in particular, desirably, the communication holes 3 a are provided in a plural number and at equal distances in the circumferential direction. Accordingly, the first connection portions 7 in which the communication holes 3 a are provided are, desirably, provided in a plural number and at equal distances are in the circumferential direction. With the above configuration, since the communication holes 3 a provided inside the first connection portions 7 are disposed at equal distances in the circumferential direction, the motor 110 can be cooled evenly in the circumferential direction. Furthermore, while the number of communication holes 3 a and the number of first connection portions 7 are each three in the present embodiment, not limited to the example described above, the numbers may each be one or a plural number other than three.

An example in which the blowing device 100 described above is mounted in a vacuum cleaner 200 will be described next. FIG. 6 is a perspective view illustrating a configuration of the vacuum cleaner 200 in which the blowing device 100 is mounted. The vacuum cleaner 200 includes the blowing device 100. In more detail, the vacuum cleaner 200 includes the blowing device 100, a nozzle 210, and a main body 220. The blowing device 100 is mounted in the main body 220. A suction brush (not shown) is attached to an intake portion 211 of the nozzle 210. The main body 220 includes a dust chamber 221 connected to the nozzle 210, a housing chamber 222 in which the blowing device 100 is housed, and an exhaust space 223 connected to a plurality of exhaust ports (not shown). An opening portion of the blowing device 100 is connected to the dust chamber 221 with a dust connection filter (not shown) interposed therebetween. In other words, a flow passage of the air suctioned by the blowing device 100 is connected from the intake portion 211, through the nozzle 210 and the dust chamber 221, and to the opening portion of the blowing device 100 in the above order. The housing chamber 222 is connected to the exhaust space 223. The airflow sent out with the blowing device 100 is discharged to the outside of the main body 220 through the exhaust space 223 and through the exhaust ports. With the above, the vacuum cleaner 200 including the blowing device 100 capable of effectively suppressing the air blowing efficiency from decreasing can be attained.

Note that the blowing device 100 in FIG. 6 is mounted in a stick-type vacuum cleaner 200; however, not limited to the example of the present embodiment described above, the blowing device 100 may be mounted in a vacuum cleaner of another type. For example, the vacuum cleaner 200 may be, for example, a vacuum cleaner of a canister type or of a handy type.

The present disclosure is suitable for an apparatus that suctions or sends out gas and that is required to have a high static pressure, for example. The present disclosure can be used in blowing devices other than a vacuum cleaner (see FIG. 6) such as an electric fan or a ventilation fan and, further, can be used in electrical appliances for other purposes such as a drying device.

Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A blowing device comprising: a motor including a rotor rotatable about a central axis extending in an up-down direction; an impeller that is fixed to the rotor and that is rotatable together with the rotor; a motor housing that is disposed on a radial direction outer side with respect to the motor and that houses at least a portion of the motor; a blower case disposed on the radial direction outer side with respect to the motor housing; and a plurality of connection portions that connect the motor housing and the blower case to each other in the radial direction; wherein the plurality of connection portions include a first connection portion including a communication hole that communicates an inner portion of the motor housing and an outer portion of the blower case to each other.
 2. The blowing device according to claim 1, wherein an opening region at a radial direction inner end of the communication hole overlaps a portion of the motor in the radial direction.
 3. The blowing device according to claim 2, wherein the motor further includes a stator disposed on a radial direction outer side of the rotor; and the opening region at the radial direction inner end of the communication hole overlaps a portion of the stator in the radial direction.
 4. The blowing device according to claim 3, wherein the stator includes a stator core provided with a coil portion; a radial direction outer lateral surface of the stator core includes: a stator first region that is in contact with an inner surface of the motor housing; and a stator second region that opposes the inner surface of the motor housing with a gap in between in the radial direction; and the opening region at the radial direction inner end of the communication hole overlaps a portion of the stator second region in the radial direction.
 5. The blowing device according to claim 4, wherein a surface of the stator includes a stator third region in which at least a portion thereof is, on an axial direction lower side with respect to the communication hole, in contact with the motor housing; and the stator third region is disposed on the axial direction lower side of the stator second region.
 6. The blowing device according to claim 4, wherein an upper end of the opening region at the radial direction inner end of the communication hole is positioned on an axial direction upper side with respect to an upper end of the stator core.
 7. The blowing device according to claim 1, wherein in an upper portion of the first connection portion a backward rotation direction lateral surface of the first connection portion is a curved surface extending towards an axial direction upper side as the backward rotation direction lateral surface extends towards a forward rotation direction, and is recessed in the forward rotation direction and towards the axial direction upper side.
 8. The blowing device according to claim 1, wherein in an upper portion of the first connection portion, a forward rotation direction lateral surface of the first connection portion is a curved surface extending towards an axial direction lower side as the forward rotation direction lateral surface extends towards a forward rotation direction, and protrudes in the forward rotation direction and towards an axial direction upper side.
 9. The blowing device according to claim 1, wherein a width of the first connection portion in a circumferential direction is larger than a width of a second connection portion, which is a connection portion other than the first connection portion among the plurality of connection portions, in the circumferential direction.
 10. The blowing device according to claim 1, wherein a largest width of the communication hole in an axial direction is larger than a largest width of the communication hole in a circumferential direction.
 11. The blowing device according to claim 1, wherein the first connection portion is provided in a plural number, and a plurality of the first connection portions are located at equal distances in a circumferential direction.
 12. A vacuum cleaner comprising the blowing device according to claim
 1. 